This invention relates to improvements in syringes and in particular to a syringe having a safety sheath and safety needle cap for preventing both needlesticks and reuse of the syringe.
Hypodermic needles, for example those used for injections or for taking blood samples, are usually equipped with a removable cap that protects and helps keep the needle sterile. The cap is usually replaceable to cover the used, contaminated needle and prevent accidental needlesticks. However, accidental needlesticks during recapping have long been a problem. Because of tension, time pressure, or fatigue, needlesticks during recapping occur with alarming frequency despite frequent warnings to be careful, and they account for a significant percentage of accidental needlesticks. Eliminating recapping will not solve the problem because the uncapped needle is so dangerous. Indeed, a large number of accidental needlesticks are caused by uncapped needles found in beds, on floors, or in garbage cans. Even where there is a no recapping policy, the needles are often recapped because of these dangers. Accidental needlesticks are serious because they can spread diseases, including hepatitis, venereal diseases, and of most recent concern: AIDS. A needlestick causes fear and anxiety in the victim. Both the victim and the patient may be subjected to a battery of expensive, timeconsuming tests. Accidental needlesticks during recapping can cost even a relatively small health care institution thousands of dollars annually. Even worse than the economic cost, however, is the transmission of disease.
For example, the victim of a needlestick from a needle contaminated by an AIDS patient must be repetitively tested after the accident. It is documented that after such a needlestick, the victim may test positive for exposure to the AIDS virus, even if the disease is not technically contracted. A positive test would cause great fear and anxiety in the victim, would seriously disrupt the victim's personal life, affect the insurability of the victim, and might even end the victim's ability to work in the health care industry.
Despite the very serious nature of the problem, and the severity of the consequences, the problem of accidental needlesticks has persisted for many years without any satisfactory solution. One approach to a solution is to modify the cap. For example, a recent article Sumner, "Needlecaps to Prevent Needlestick Injuries", INFECTION CONTROL (1985) Vol. 6, No. 12, p. 495, discusses the needlestick problem and discloses a needlecap with a small, wide angle funnel surrounding the cap opening. This funnel acts as both a guide and a shield. However, improvements to the cap do not totally eliminate the possibility of needlesticks. The action of bringing the cap and needle together still poses the threat of an accidental needlestick.
Another approach to a solution is to provide a sheath that can be slid down over the needle from behind, eliminating the risky action of bringing the cap and needle together. Various sheath devices have been patented, for example those disclosed in U.S. Pat. Nos. 4,425,120, 3,780,734, and 2,571,654. However, these devices were too complicated and very difficult and expensive to manufacture, and have never been widely available.
Still another approach to a solution has been to provide a syringe having both a needle cap and a sheath. This combination is shown in U.S. Pat. No. 4,425,120. However, the needle cap of this device is a conventional needle cap and it offered no protection against a needlestick when recapping the syringe. Furthermore, the sheath of this device was too complicated and very difficult to use.
This invention addresses the limited effectiveness of policy changes such as the "no recapping" policy adopted by the CDC. In a study reported in the Jan. 19, 1986 issue of HOSPITAL EMPLOYEE HEALTH, Bellevue Hospital Center in New York adopted new needle safety policies and procedures in 1983 which included a "no recapping" policy. In spite of a three month intensive promotional effort which included newsletters, memos, and an in-service educational program for the hospital staff, the incidence of needlestick injuries did not significantly change. Indeed, 13% of the injuries were from recapping needles in spite of the "no recapping" policy. Thus, this invention offers significant protection and additional safety for what some would call a common but improper use of the needle and syringe, i.e. recapping the needle.
Because of the problems with inadvertent needlesticks, numerous hospitals have adopted the "no recap" policy with regard to various needle caps. However, a safe method of recapping needles is advantageous for preventing needlesticks. Furthermore, despite contrary policy and instructions many of the medical personnel recap the needles anyway. The combination of the sheath and the cap of the present invention provides a synergistic affect that rebuts reasons against using either the cap or the sheath individually without the other. Thus, safety is increased for the common usages of the needle and syringe, which has repeatedly been shown to include recapping and disposal without recapping, regardless of policy.
The present invention features the combination of a special needle cap which can fit within a special sheath slidably mounted to the barrel of a syringe. The needle cap is sized to fit about the needle to prevent it from sticking into another. The sheath used in combination with the cap is slidably mounted over the barrel of the syringe. The sheath can be locked in a retracted position in which the needle cap extends beyond the sheath. The sheath can be moved to an extended position relative to the barrel. In being so extended, the sheath slides about the cap so that the cap is contained within the sheath. The sheath can be locked relative to the barrel in both the retracted and extended positions.
In use, the sheath can be mounted to the barrel in the retracted position. The cap can be mounted to the syringe to cover the needle. The cap can then be removed so that the syringe can be grasped and the needle used to inject the syringe contents into a patient. After the needle is removed from the patient, the sheath can be moved to the extended position and locked so that the sheath extends beyond the tip of the needle. This prevents inadvertent needlesticks.
Then, with the sheath extended, the cap can be moved to fit about the needle. The cap is inserted within the sheath with the cap's open end about the needle tip. The cap is moved into the sheath to completely fit about the needle, and be attached to the syringe, or to the sheath, and held in the capping position.
With the sheath extended in such fashion, one can observe that the syringe has been used even when the needle is capped. Thus, any reuse of this needle is prevented. With the recapping performed while the sheath is in the extended position, there is extra protection against a needlestick, since the cap can be moved toward the needle with the sheath guarding the operator's hands from the needle. Further, when the cap is remounted, the extended sheath blocks any inadvertent forces that otherwise might be directed against the cap to dislodge it from the syringe.
The inventors herein have developed the combination of a syringe with a safety sheath and a safety needle cap that reduces the possibility of needlesticks during recapping of the syringe after use. The combination of the sheath and cap also helps prevent needlesticks caused by needles found in beds, on floors, or in garbage cans. The safety sheath serves as both a guard to shield the needle during recapping and a visual indicator to show when the syringe has been used. There are some environments which require that a syringe be used only once and then disposed. The syringe of this invention could be effectively used in these environments.
In an embodiment of the invention, the syringe has at least one knob projecting outwardly from the barrel. The sheath also has at least one longitudinal slot for receiving the knob. The slot has a first set of opposing tabs projecting into the slot, the lower faces of which engage the top of the knob to retain the sheath in its retracted position. The lower faces of the first set of tabs are angled. These angled lower faces force the tabs apart to clear the knob when the sheath is forced downwardly against the knob. The slot also has a second set of opposing tabs projecting into the slot above the first set. The second set of tabs have angled lower faces and flat upper faces that form a shoulder. The angled lower faces force the tabs apart to clear the knob when the sheath is forced downwardly against the knob. The tabs resiliently snap back after clearing the knob, and the shoulders formed by the upper faces of the tabs engage the bottom surface of the knob and lock the sheath in the extended position.
The sheath is retained in its retracted position relative to the syringe until positive force is applied to overcome the resistance of the first set of tabs. The sheath is easily moved to its extended position by simply pushing the sheath downward. The sheath is easily locked in its extended position by simply pushing the sheath all the way down until the second set of tabs engage the knob. This positive locking action requires no special alignment or manipulation and it is easy to visually confirm.
The needle cap in an embodiment of the invention is a generally cylidrical, hollow tube closed at one end and open at the other end to receive the needle. The cap combined with the sheath provides advantages over the art. Further, the cap can have an outwardly facing funnel-shaped lip surrounding the open end to channel an errant needle into the opening and to protect the fingers gripping the cap, combined with means to space the fingers from the opening in the cap. These spacing means can be a plurality of radial splines extending between the exterior wall of the cap and the funnel-shaped lip to support the lip and to keep the user's fingers spaced from the cap opening. Alternatively, or additionally, a guard may project radially from the cap intermediate the ends of the cap. This guard can serve as secondary protection.
The combination syringe of the present invention is of simple construction and will be easy and inexpensive to make and simple to use. The locking action is positive and visually confirmable and without any special manipulation that can be improperly done. The cap may be used on any of the needle structures presently in use including disposable syringes.